Electronic discharge device



March 31, 1942. A. M. SKELLETT 2,277,858

ELECTRONIC DISCHARGE DEVICE .lA/VENTOR :1. M SKELLETT A T TORNE V March 31, 1942. M SKELLETT 2,277,858

ELECTRONIC DISCHARGE DEVICE Filed May 17, 1941 3 Sheets-Sheet 2 lNl/ENTOR AM SKELLETT BY 29 Q lm. M

A T TORNEV A. M. SKELLETT ELECTRONIC DISCHARGE DEVICE March 31, 1942.

Filed May 17, 1941 3 Sheets-Sheet 5 lNl ENTOR AM. SKELLETT ATTORNEY Patented Mar. 31, 1942 ELECTRONIC DISCHARGE DEVICE Albert M. Skellett, Madison, N. 1., asslgnor to Bell Telephone Laboratories, Incorporated, New York, N. Y., a corporation of New York Application May 11, 1941, Serial No. saaszr 11 Claims. (01. 250-215) This invention relates to electronic discharge devices and more particularly to devices having multicontrol elements for electronic switching applications in the electric and communications arts.

In prior devicesqcomprehended by this invention, the cathode or-electron source is surrounded by an output electrode or anode, the spacing therebetween being maintained at a minimum to achieve the purposes of the device, and intermediate these work electrodes a group of wire control elements or grids are positioned in parbeing spaced the same distance from the cathode and anode.

When a large number of wire grid elements are provided and confined to a restricted diameter of the electrode area. the wires. are necessarily of small diameter and easily distorted by mechanical handling andheat treatment, thereby materially altering the control characteristics of the device. Furthermore, the wire grid elements aredifilcult to hold in proper alignment with other associated electrodes.

An"obj ect of this invention is to improve the mechanicaland electrical efficiencies of mu1tigrid discharge devices.

Another object of the invention is to insure accurate space relationship of the multigrids with other cooperating electrodes.

A further object of the invention is to control the amplification factor and plate resistance characteristics of such devices within certain limits, while maintaining the transconductance substantially constant.

In accordance with this invention, the difficulties of prior devices are overcome and the above objects are attained, in one aspect of the invention, in which a central cathode ,or electron source is surrounded by stacked annular disclike control elements, each being individually provided with a conductor sealed in the vessel wall to impress a suitable potential thereon. The

rigid assembly of the stacked discs insures strength and positive alignment both with re- :spect to each other and to other electrodes associated therewith. Furthermore, the control elements may be increased to any desired number dependent on the length of the assembly and the spacing between the elements without sacrificing accurate spatial relation with respect to axial relation in a circular boundary, each grid relation with the grid elements, the anode discs being connected to a common terminal conductor sealed into the vessel.

A feature oi! the invention relates to'the unltary mounting of the assembly involving multidisc-like grids and anode elements in which the elements are supported in rigid spatial relation by end spacer members carrying cushion spacers engaging the wall of the vessel, the elements being coupled to conductors radially sealed through an annular rim of the vessel.

Another feature of the invention relates to the stacking of the elements in coaxial relation to a central cathode to insure positive interspatial relation therebetween and provide accurate alignment and definite symmetry between the cooperating electrodes of the unit. This is accomplished by forming the disc-like elements with an annular central portion of suitable dimensions and outwardly projecting ears or tabs punched to receiving insulating pillars and intermediate spacers between the elements to rigidly flx the location of the electrodes.

These and other features of the invention will be apparent from the following detailed description taken in connection with the accompanying drawings:

Fig. 1 is a perspective view of one embodiment of the invention with parts of the vessel and the internal electrodes broken away to clearly illustrate the assembly of the unit.

- illustrate the relationship of the electrodes in the unit and the provision of the individual conductors for the multigrid elements.

Fig. 3 is a plan view of the device of the invention taken on line 3-3 of Fig. 2 showing the disposition of the conductors. with respect to the stacked electrodes of the unit.

4 is a plan view of the lower end of the device taken on line 54 of 2.

Fig. 5 is an enlarged fragmentary view of the various details entering into the support of the elements in the lower spacer member.

Fig. 6 is an enlarged view in perspective partly in section showing details of stacking the con: trol elements in the unit.

Fig. 7 illustrates in elevation a modification of the invention in which the anode is formed of discs similar to the control elements.

Fig. 8 is an enlarged perspective view of details of the elements of Fig. 'I, in which-the grid and anode disc elements are shown in" partly assembled relation; and,

carrier coated with electron emissive material,

such as the oxides of alkaline earth, and an internal heater element l3 for energizing the cath ode coating by conduction to facilitate the emission of electrons from the coating. The cathode is centrally supported at opposite ends by circular spacing discs l4 and I5 of suitable insulating material, such as mica, the discs being provided with spaced outwardly projecting ears I 6 which carry vertical insulating strips of mica I! so that the flexible ends of the strips contact the inner wall of the vessel l0 and contribute to the support of the unit.

Opposed to the cathode and longitudinally po- I sitioned on opposite sides thereof are two curved plate sections l8 and I9 which are secured to pairs of upright wires extending through the spacing discs I4 and I5. These plate ,sections form the anode or output electrode of the unit. Be tween the cathode and the anode, a plurality of annular disc-like elements 20 are positioned to coa'xially surround the cathode and form multicontrol elements. By varying the potentials on any one of the elements, the electrons in its vicinity may be controlled in their travel from the cathode to the anode so that suitable switching problems may be achieved by electrostatic control of the electron discharges in the device.

The construction of the multicontrol elements may be more clearly understood from a reference to Fig. 6 which shows an annular disc-like element 20 having an integral ear 2! extending radially from the circumference of the element and an elongated extension 22 diametrically opposite the ear 2|, the extension 22 being provided with an aperture equally spaced from the circumference of the element, the same as the ear 2|. These disc-like elements are mounted in coaxial relation with respect to the cathode with the long extension 22 projecting in opposite directions in alternate tiers and the ears 2| alternating with the extensions 22 of adjacent elements. These elements may be punched from sheet 'metal, such as nickel or aluminum, with a suitable die to insure accurate similarity between all the elements. The multidisc elements are l2 between the spacing discs l4 and I5 and are mounted. therein by metallic eyelets 25 secured in accurate position in the discs. The upright rods are surrounded by insulating sleeves 26, of aluminum oxide or similar insulating material, and of such diameter to pass through the apertures in the disc-like elements 20 thereby insulating the elements from thesupport rods 23 and 24. The elements are stacked in successive relation and equally spaced with respect to each other by spacing collars 21, of insulating material similar to the sleeves. This construction insures accurate alignment of the disc-like elements with respect to each other and also with respect to the cathode and anode of the device and insures proper segregation of the multielements embodied in the unit so that leakage between them is eliminated. Furthermore, the stacking arrangement insures rigidity in the whole assembly and increases the efliciency of operation and constancy in the characteristics of the device. This construction of the multicontrol elements of the device and the mounting thereof also insures the alignment and coaxial relation of the control elements, so that uniform control conditions are realized regardless of the number of control elements embodied in a given assembly. The short collars 21 insure accurate and uniform space relationship between all of the control elements and adequately insulate the respective elements from each other and the remaining components in the unit. Furthermore, the insulation encased standards 23 and 24 arranged on opposite sides of the cathode facilitate the staggering of the long extensions of the elements to segregate the numerous elements and enable the coupling of multiple conductors carried by the vessel to the individual elements. The stacked assembly provides constant concentricity of the control elements 20 with respect to the cathode and also eliminates distortion of the annular portion of the elements with respect to the long extensions 22 which project laterally from opposite sides of the stacked assembly. The cathode I 2 is also supported from the parallel standards by a strap 28 mounted below the lower insulator IS, the cathode being connected to the centre of the strap and the ends thereof being welded to the eyelets 25 below the disc I5. The terminations of the heater element I3 extend to short rods 30 and 3! and are welded thereto, the rods-being secured to the insulating disc 15 by eyelets 32.

After the unit is assembled as heretofore described, it is placed in the vessel III with the top of the unit spaced from the dome of the vessel by the contacting edges of the spacers I! at opposite ends of the unit, the dome of the vessel preferably being coated with an opaque film of magnesium which is vaporized from a getter material supported in the crimped portion of the plate amounted on an extension of the standard 23. The lower end of the vessel is'provided with a rim seal 34 which is in the form of an annular rib projecting from the circumference of the vessel. This rib forms a sealed Joint for a plurality of radially directed conductors such as 35, equal in number to the annular disc-like grid elements 20 in the electrode unit, the conductors being distributed in spatial relation with their outer ends spaced apart a greater distance than the ends within the vessel as shown in Fig. 4. Since there are twenty grids in the device as .shown in Fig. 2, it is necessary to provide the same number of conductors 35 in the rib seal to facilitate individual connection to the grids and accomplish the multi-switching action capable of being performed in accordance with this invention. The rib seal also includes a suitable conductor, such as 38, for the anode l8 and conductors 31 for supplying energy to the heating element l3 of the cathode, the cathode also being connected to one of the heater leading-in conductors 31 by a wire connection 38 coupled between the eyelet 25 and the rod 30 to which the conductor 31 is attached. The radial conductor 36, as shown in Fig. 4, is connected to the center of the crosspiece 39 which bridges the support rods for the anode l8 extending below the insulator IS. The grid elements 20 are coupled to their respective leading-in conductors 35 through angle-shaped stamens tions of the device. Furthermore, the radial disposition of the grid element conductors insures adequate insulation between the various elements -so that leakage or short-circuit does not easily occur in the operation of the device.

A modification oi the invention is disclosed in Figs. '1 to 9, inclusive, in which the grid control elements are slightly modified as shown at 42 in which the aperture therein is smaller than described in connection with the previous figures to attain ahigher transconductance characteristic by reducing the space relation between the cathode and the grid elements. The anode in this embodiment is formed of a plurality of ringlike elements 43 having outwardly extending portions ll and I which are stacked alternately with the grid elements on the support standards 23' and", the anode elements having a larger internal-diameter than the grids 42 so that the" space discharge is equally distributed along the whole length of the cathode in relation to the grid elements and the anode elements. The an-.

ode elements 43are connected to a longitudinal wire 46 extending through the end insulators ol the unit by short stub wires II, the longitudinal support wire 46 being connected to a radial conductor 48, as shown in Fig. 9. The conductors I! extend radially below the unit and are attached to the support rods 30 to which the ter- What is claimed s:- 1. An electronic switching device comprising an enclosing vessel, a unitary mount within said vessel containing a central electron emitting cathode, a plurality of control elements adjacent said cathode. said elements having central apertured disc portion coaxially surrounding said cathode and outwardly extending portions fixed in linear and superimposed relation on opposite sides ofsaid cathode, insulating means spacing said elements and mounted coextensive with said cathode, anode means cooperating with said cathode and control elements, and conductors passing through the wall of said vessel connected to said cathode, anode and control elements.

2. An electronic switching device comprising an enclosing vessel, a unitary mount within said vessel containing a central electron emitting cathode, a plurality of annular fiat control elements insulatingly stacked in successive spaced layers about said cathode, an anode'inember 00- operating with said cathode and said control elements, spacer discs out-opposite ends of said cathode, control elements and anode, a pluralminati ns 29 of the heater are connected. The

cathod is attached to a radial conductor 50 which extends diametrically opposite to the anode conductor It in the rib seal 31, the remaining'ten radial conductors 5! being provided for the ten grid elements in the unit shown in Fig. 7 through the angle connectors 52 similar to the grid connectors 40 in Fig. 1. By the modification of the elements of the interleaved or stacked anode and grid elements, a large range of plate resistance and amplification factor may be I681".

ized with substantially constant transconductance.

In the operation of the devices of this invention for multiswitching applications, the grid elements are normally biased at 40 volts with a .plate voltage of 120 volts. Then if one of the grids is grounded by suitable circuit facilities connected to the grid a current of 2.5 milliamperes is realized in the anode circuit for producthe compact unit of this invention, it is, of course,

ity of current conductors radially sealed through a circumferential portion of said vessel, and connectors passing through one of said discs near the periphery thereof and coupled to said conductors and said elements.

3. An electronic switching device comprising an enclosing vessel, a central cathode therein, a plurality of control elements cooperating with said cathode, said elements having a central apertured disc portion coaxially surrounding said cathode and outwardly extending portions fixed in linear and superimposed relation on opposite sides of said cathode, insulating means spacing said elements and mounted coextensive with saidcathode, the extending portions of alternate elements projecting beyond said insulating means on opposite sides of said cathode, an anode cooperating with said cathode and control elements, and radial conductors in said vessel joined respectively to the alternate extending portions of said elements.

4. An electronic switching device comprising an enclosing vessel, a. unitary mount within said vessel containing a central electron emitting cathode, a plurality of annular fiat control elements insulatingly stacked in successive spaced layers about said cathode, an anode member cooperating with said cathode and said control elements, a plurality of current conductors radially sealed through a circumferential portion of said vessel, and a plurality of connectors extending laterally upward from said conductors and having the ends thereof bent towards the elements in successive planes.

5. An electronic switching device comprising an enclosing vessel having an annular rim near one end thereof, a central cathode in said vessel, insulating spacers at opposite ends of said cathode, parallel supports connected to said spacers and positioned on opposite sides of said cathode, a plurality of annular flat metallic grid members surrounding said cathode, said members having outwardly extending arms securedto said supports, insulating collars interposed between adjacent members on said supports to insulate and stack said members in coaxial alignment, and anode formed of arcuate plate sections longitudinally supported by said insulating spacers and partially surrounding said cathode and said grid members, a plurality of radially disposed conductors sealed into said annular rim, and a plu-= 'rality of connecting wires between said conducoutwardly extending arms secured to said supports, an anode formed of arcuate plate sections longitudinally supported by said insulating space ers and partially surrounding said cathode and grid members, a plurality of radially disposed conductors sealed into said annular rim, and a plurality of connecting wires between said conductors and said grid members, said wires extending through one of said insulating spacers near the periphery thereof in transverse relation to the respective radial conductors, the other end of each wire being bent inwardly in the plane of its respective grid member and attached to an arm thereof.

7. An electronic switching device comprising an enclosing vessel having an annular rim near one end thereof, a central tubular cathode, a heater element within said cathode, insulating spacers at opposite ends of said cathode, a plurality of annular fiat metallic grid members insulatingly stacked in successive spaced layers about said cathode, an anode formed of arcuate plate sections longitudinally supported by said insulating spacers and partially surrounding said cathode and grid elements, a pair of rigid rods dxtending below the lower insulating spacer, said heater element being connected to said rods, means for coupling said arcuate plate sections, a plurality of radially disposed conductors sealed into said annular rim, certain of said conductors being connected to said rods and coupling means for said anode, and a plurality of connecting wires joining said elements to the remaining conductors.

8. An electronic switching device comprising an enclosing vessel having an annular rim near one end thereof, a central cathode therein, insulating spacers at opposite ends of said cathode, parallel supports connected to said spacers and positioned on opposite sides of said cathode, a plurality of annular fiat metallic grid elements surrounding said cathode, said members having outwardly extending arms secured to said supports in insulated and stacked spaced relation, an anode longitudinally supported by said insulated spacers and partially surrounding said cathode and grid elements, a plurality of radially disposed conductors sealed into said annular rim, and a plurality of connecting wires between said conductors and said grid elements, said wires extending through one of said spacers near the periphery thereof in a circular boundary, the wires located in one half of the spacer being connected .to the arms of alternate grid members on one side rality of apertured disc anode elements alternately spaced around said cathode with respect to said grids, the aperturededges of said elements being spaced a greater distance from said cathode than the inner edges of said grids, a common terminal connection for said elements sealed through the wall of said vessel, and separate lead-in conductors for each of said grids sealed through the wall of said vessel in the plane of said terminal connection.

10. An electronic switching device comprising an enclosing vessel having an annular rim, a

central cathode therein, insulating spacers at opposite ends of said cathode, a pair of parallel supports connected to said spacers and positioned on opposite sides of said cathode, a plurality of annular flat metallic grid members surrounding said cathode, said members having integral arms secured to said supports, a plurality of annular flat metallic anode elements interposed alternately between said grid members and having integral arms secured to said supports, insulating collars surrounding said supports and spacing said grid members from said anode elements in coaxial relation, a plurality of radially disposed conductors sealed into said annular rim, means for coupling all of said anode elements together, said means being connected to one of said conductors, and a plurality of connecting wires between the other conductors and said grid members.

11. An electronic switching device comprising an enclosing vessel having an annular rim seal, a plurality of radial conductors extending through said seal, an electrode mount in said vessel positioned beyond said seal, said mount comprising a pair of insulating discs held in spaced relation, a pair of parallel supports extending between said discs, said supports having insulating sleeves thereon, a plurality of annular thin metallic control members coaxially positioned between said supports, each of said members having a short integral arm on one side and a long integral arm on the other side, said arm engaging said sleeves in alternate relation, insulating collars spacing adjacent members on said sleeves,

a tubular cathode within said annular members and equally spaced from the respective members, an anode mounted longitudinally between said insulating discs in cooperative relation to said cathode and control members and positioned outside of said members, and a plurality of connecting wires coupled to a majority of said radial conductors and extending vertically through the lower disc, said wires having their ends bent at an inward angle in the plane of the respective control members and coupled to the long arms thereof.

ALBERT M. SKEILET'I. 

